Old Plates and the Sea

摘要

Estimates for the area and age of the ocean floor are at odds with assumptions for mantle convec-:ion, which imply that an older sea floor-rather :han a new one-would be preferentially subducted over time. Previous efforts to explain these relationships have been based on geologic evidence and simple models. Coltice et al. (p. 335) created numerical three-dimensional convection models representing more realistic physical boundaries, including a spherical Earth, the existence of continents and supercontinents over time, and realistic rheologies. A combination of continents and plate-like behavior of the ocean floor sufficed to produce the observed relationship between plate area and plate age, which explains why some old oceanic crust still remains.